Generally speaking, color has three characteristics or aspects that contribute to what people see. These characteristics (also called color factors herein) are hue, saturation, and value. The hue of a color is the point along the human visual spectrum of colors, real or perceived, (e.g., red, orange, yellow, green, blue, violet, and magenta) that the color falls. The saturation (also called chroma) is the purity of the color. The value (also called brightness or luminosity) is the lightness or darkness of the color.